On June 26, 2018, the German Federal Institute for Risk Assessment (BfR) published a Q&A document on the use of reusable coffee to go cups at shops that accept the practice of customers bringing their own refillable hot drink containers.
Regarding hygiene, the BfR stressed that reusable coffee to go cups should be emptied and cleaned by the consumer before refilling. The BfR recommends regular cleaning of the cup with hot water and dishwashing detergent and letting it dry completely. The agency further advises that the cup should not touch the filling nozzle of the coffee machine while refilling.
The BfR deems materials with smooth and easy-to-clean surfaces such as porcelain, stainless steel, inherently and temperature-stable plastics, or glass suitable for coffee to go cups. The agency noted that the cups must be compliant with the regulations in force regarding the migration of chemicals of concern from the article to the food. Further, the materials should be dishwasher- and heat-proof, and ideally also disinfectant-proof and corrosion-resistant. The BfR recommends using the cups only as long as their surface is smooth, without cracks or signs of wear.
So-called “natural” materials, such as bamboo, are also used for the production of coffee to go cups and other food contact articles (FCAs). For the main part, they consist of plastics such as melamine resin, the BfR explained. Melamine resins are polymers consisting of the monomers melamine and formaldehyde, the BfR further clarified. The “natural” materials are mainly used as filling materials in these compositions. Cups made of melamine resin should only be used at temperatures up to 70° C, the agency advises. In 2011, the BfR published a statement on the migration of melamine and formaldehyde from melamine resin FCAs into food.
BfR (June 26, 2018). “Fragen und Antworten zur Nutzung kundeneigener Mehrwegbecher für ‘Coffee to go.’” (in German)
BfR (June 26, 2018). “Fragen und Antworten zur Nutzung kundeneigener Mehrwegbecher für „Coffee to go.’” (pdf; in German)
BfR (March 9, 2011). “Freisetzung von Melamin und Formaldehyd aus Geschirr und Küchenutensilien.” (pdf; in German)